Treatment of iron or steel for preventing oxidation or rusting.



I UNITED STATES PATENT orFroE.

THOMAS WATTS COSLETT, OF BIRMINGHAM, ENGLAND.

TREATMENT OF IRON OR STEEL FOR PREVENTING OXIDATION OR RUSTING.

Specification of Letters Patent.

Patented Nov. 12, 1907.

Application filed April 9. 1907. Serial No. 367.154.

To all whom it may concern:

Be it-known that THOMAS WATTS GOSLETT, a subject of the King of GreatBritain, residing at 17 Jamaica Row, Birmingham, in the county ofWarwick, England, manufacturing chemist, has invented certain new anduseful Improvements Relating to the Treatment of Iron 01' Steel forPreventing Oxidation or Rusting, of which the following is aspecification.

i This inyc'iition relates to improvements in the kind of treatment ofiron or steel for preventing oxidationor rusting? in which the iron orsteel, or articles composed or having a surface of iron or steel is orare provided with a protective covering adapted to render the surfacesthereof capable of resisting, or of being unaffected by, the action ofmoisture and other oxidizing or rusting influences.

It has heretofore been proposed to treat iron with glacial, phosphoricacid andalso to treat iron wire with the said acid dissolved in waterwith the object of preventing rust; 1 would therefore have it understoodthat the treatment according to my invention differs from these previousproposals in that the iron or steel is subjected to the action of adilute solution of ordinary phosphoricacid, whereby I effect a depositthereon consisting of a mixture of normal' ferric and ferrous phosphateof iron.

According to this invention, the iron or steel or the articles composedor having a surface of iron or steel is or are subjected to treatmentwhich has the effect of furnishing the same with acovering or deposit ofphosphate of iron; whereby it is found that the metals or articles arerendered immune from the deleterious influence of oxidation or rusting.

In carrying out the invention, the iron or steel or the article composedor having a surface of iron or steel is immersed in, or otherwisesubjected to, the action of a compound consisting of a dilute solutionof ordinary phosphoric acid, a suitable substance, such as iron filingsferrous phosphate or other appropriate compound, being also employed forthe purpose of controlling or regulating the rapidity or strength of thechemical action upon the metal or articles undergoing treat ment; theemployment of a controlling or regulating material although preferableis not however indispensable, the essential feature of the inventionbeing the protective covering or deposit of the aforesaid phosphate ofiron which, in some instances, may be produced by subjecting the iron orsteel surface or article to the action of a dilute solution ofphosphoric acid aloneor by passing an electric current through a dilutesolution of ordinary phosphoric acid with (or without) the addition ofan appropriate substance or compound adapted tofcontrol or regulate thechemical reactions.

A solution or composition which has been found to give satisfactoryresults, may contain the following ingredients or substances in or aboutthe proportions given, viz:

Iron in the form of filings or powder 1 ounce. Phosphoric acid,concentrated .4 fluid ounces.

v Water .160 fluid ounces.

For the purpose of my invention a quantity of the solution containingthe above mentioned ingredients may be placed in an enameled iron bathor other vessel and heated to the boiling point, whereupon the metal orthe article or articles to be treated, after being thoroughly cleaned,is or are immersed therein, and the solution or composition evaporated.to any desired extent, as for example, to about one seventh of itsoriginal volume. The articles thus treated may then be with drawn, and,after being thoroughly wiped and dried, may be oiled preparatory to use.

The coating or deposit, produced upon the surface of the article, by theprocess above described, which consists of phosphate of iron, may bestrengthened or thickened if necessary by repeating the process, or byadding a further quantity of phosphoric acid and iron filings or powderto the solution after partial evaporation, and then diluting andrevaporating.

Should the coating or deposit be undesirably thick, the excess mayreadily be removed by subjecting the coated article, upon withdrawalfrom the bath, to treatment by cold water. If it be desired to vary thetone or color of the coating or deposit, the metals after completion ofthe aforesaid process may be immersed in a cold or boiling solutioncontaining substances such as sulfids, tannic acid or such substancesmay be used in the original bath together with the other ingredientsbefore mentioned. Discretion should, however, be exercised in theselection and employment thereof so as not to impair the efficiency ofthe coating or deposit of phosphate of iron.

Various mechanical contrivances may be employed for carrying out theprocess of immersion or treatment. For instance, the articles may beinclosed by a screen or cage whereof the walls are perforated orconstructed of wire, muslin or other cotton or woolen fabric of such amesh as will prevent the passage of fine particles, such as the ironfilings, when used, while permitting of the free passage of thesolution.

The above mentioned screen or cage may be used in conjunction with acage or drum adapted to be rotated so as to effectually bring thesurfaces to be treated under the action of the solution, but moreparticularly to prevent irregular deposits. If rotary motion may beemployed the first mentioned inclosing cage or screen may in some casesbe dispensed with.

What I claim and desire to secure by Letters Patent of the United Statesis:- I

1. The treatment of iron or steel or articles composed or having asurface of iron or steel, consisting in subjecting the same to theaction of a dilute solution of ordinary phosphoric acid whereby adeposit is efiected thereon of phosphate of iron for the purposesspecified.

2. In the treatment of iron or steel or articles composed or having asurface of iron or steel, a compound consisting of a dilute solution ofordinary phosphoric acid substan' tially as and for the purposesspecified.

3. In the treatment of iron or steel or articles composed or having asurface of iron or steel, a compound consisting of a dilute solution ofordinary phosphoric acid with the addition of a substance adapted tocontrol or regulate the chemical reactions, substantially as and for thepurposes specified.

4. In the treatment of iron or steel or articles composed or having asurface of iron or steel, the solution or composition consisting ofordinary phosphoric acid, iron and water, in or about the proportionshereinbetore stated.

5. A protective covering for iron or steel or articles composed orhaving a surface of iron or steel comprising,

as an essential constituent, normal ferric and ferrous phosphate ofiron, for the purposes specified.

6. Iron or steel or articles composed or having a surface of iron orsteel furnished with a coating or deposit of phosphate of iron,substantially as hereinbetore described for the purposes specified.

-7. In the treatment of iron or steel or articles composed or having asurface of iron or steel, eflecting a coating or deposit thereon ofphosphate of iron by passing an electric current through a dilutesolution of ordinaryphosphoric acid.

8. In the treatment of iron or steel or articles'composed or having asurface of iron or steel, effecting a coating or deposit thereon ofphosphate of iron by passing an electric current through a dilutesolution of ordinary phosphoric acid with the addition of a substanceadapted to control or regulate the chemical reactions.

In testimony whereof I aflix'my signature in presence of two witnesses.

THOMAS wa'r'rs cosLE'r'r.

Witnesses:

Esmas'r Hsnxns, E. M. WEBB.

